The present invention relates to detackified polymeric sizing compositions for fiberous materials, and to a method of producing detackified, sized fiberous materials. More particularly, the present invention is directed to detackified polymeric sizing compositions for treating glass fibers and methods for producing detackified, sized glass fibers.
In the commercial production of glass fiber strands, a multitude of fine glass filaments are combined to yield the glass fiber strand. These fine glass filaments are formed by the rapid attenuation from molten cones of glass at the tips of small orifices in a bushing, for example, as in the operation shown in U.S. Pat. No. 2,133,238. In order to protect the glass filaments from interfilament abrasion, the filaments are coated during their formation with a sizing composition to protect the glass fiber strand against handling equipment during further processing, and to give the glass fiber strand integrity and workability for any standard textile or reinforcement use. After the filaments have been treated with sizing composition, they are gathered together into a strand and the glass fiber strand is wound around a rapidly rotating drum to form a package. Since the sizing composition used to treat the glass filaments is an aqueous composition, the treated glass filaments gathered into a strand and wound into a package generally contain enough moisture to give the package a wet appearance. In order to remove some of the moisture from the package to produce dry glass fiber strand, the packages are dried in ovens for a desired period of time.
The sizing compositions usually contain one or more components such as a lubricant, a film former or binder, a coupling agent, and possibly other additives like flexibilizing agents, wetting agents, stabilizers, plasticizers and emulsifying agents and the like. When glass fibers are used to reinforce polymers, either thermoplastic or elastomeric polymers, the size contains, at a minimum, a lubricating agent and a film former. The types of film formers that can be used in the sizing composition include polyesters, polyvinylpyrrolidones, epoxy resins, polyamides, polyacrylates, polyvinyl alcohols, starches, and homopolymers and copolymers of butadiene and derivatives thereof such as hydroxy, carboxy, nitrile, etc. terminated butadiene polymers. When the size contains a film forming material, the tacky nature of the specific polymer used as the film former can impede further processing of glass fibers treated with a sizing composition containing the polymer. The processing difficulties arise during various further production operations such as when the glass fiber strand has to be removed from the dried wound package, when the glass fiber strands are chopped for use as reinforcement, and when the strands are processed in a manner that entails the contact of the tacky surfaced strand with contact points such as guide eyes, rollers, chopping blades and the like.
The tack problem in removing the glass fiber strand from the package occurs because the strands are wound onto the package at rapid rates and dried, and as a consequence any tackiness of the sizing composition results in inter-adhesion or blocking of adjacent or contacting segments of the strand when it is removed from the package. The tack problem also occurs in the additional processing of the glass fiber strand to produce woven products, roving, and the like, wherein a myriad of packages are placed on a creel and the numerous glass fiber strands removed from the packages are passed over contact points, guide eyes and the like to a common destination. This tack problem in such an operation would reduce the efficiency of the glass fiber strands reaching the common destination in a satisfactory condition, because the tackiness would lead to build-up on the passages, contact points and guide eyes thereby increasing the frequency of breakage of the strands and the fuzziness of the strands. In the production of chopped roving products, the tack problem would decrease the efficiency of chopping by causing some strands to be chopped improperly and by causing chopped strands not to break apart. If the chopping of the roving is to occur in spray-up apparatus where the strands are chopped and sprayed simultaneously, the tack problem would reduce the efficiency of the roving separating into individual strands where each strand would contain several hundred glass fibers. This operation could lead to clumps or aggregates of glass fibers upon the mold or forming surface on which the glass fiber polyester resin mixture is sprayed.
The art in trying to reduce the amount of tack for glass fiber strand treated with sizing compositions containing polymer film formers has developed a number of fillers, anti-blocking agents, and detackifiers that can be added to the sizing composition that is used to treat the glass fibers. The addition of such agents to the sizing composition is not without accompanying disadvantages. Disadvantages that may result from addition of such agents include: diminished protective capability supplied by the sizing composition to the glass fibers, increased susceptibility of the glass fibers to moisture adsorption, and increased dryability and stiffness of the glass fiber strands. Such disadvantages would decrease the effectiveness of the glass fiber strands as reinforcement for either the thermoplastic polymers and/or elastomeric materials.
Another approach to reducing the tack of tacky resins used in the sizing compositions was proposed in U.S. Pat. No. 3,409,577 (Wong et al). This approach was to use a detackifying agent which was believed to have one end which was non-tacky by reason of a particular type of detackifying group. The detackifier adheres to the surface of tacky materials in an oriented manner with the non-tacky group projecting from and covering the surface of the normal tacky materials. The type of detackifying agents useful in this approach were those having the following formula: ##STR1## wherein Y is a member of the class consisting of hydrogen, an alkyl radical of a chain length of from 1 to 7 carbon atoms, and X is a member of the group consisting of:
(1) an aliphatic hydrocarbon having a chain length of from 1 to 7 carbon atoms and including at least one hydroxy group, PA1 (2) --OH, and PA1 (3) --(OR") and OH, wherein R" is an aliphatic hydrocarbon radical having a chain length of from 1 to 6 carbon atoms, and n is an integer from 1 to 25, and R is a long chain organo molecule having a molecular weight up to approximately 10,000 devoid of the terminal group given above at its other end.
It is an object of the present invention to provide a sizing composition for glass fibers that produces sized glass fiber strand with reduced tackiness without incurring the disadvantages of using detackifying agents in the sizing composition.
It is an additional object of the present invention to provide a method for producing sized glass fiber strands that have reduced tackiness.
It is a further additional object of the present invention to provide a sizing composition for treating glass fibers that yield treated glass fibers capable of having better wetting, better penetration and better encapsulation of the glass fibers when coated with an elastomeric coating to produce elastomeric coated cord.
It is another further additional object of the invention to provide a sizing composition for treating glass fibers that yields a treated glass fiber strand capable of having good wetting, penetration, and encapsulating characteristics for use in reinforcement of thermoplastic polymer matrices.